title: Effects of the carrier frequency of interferential current on pain modulation in patients with chronic nonspecific low back pain: a protocol of a randomised controlled trial.
abstract: BACKGROUND
  Low back pain is an important public health problem that is associated with poor quality of life and disability. Among the electrophysical treatments, interferential current (IFC) has not been studied in patients with low back pain in a high-quality randomised controlled trial examining not only pain, but pain mechanisms and function.
  
  
  METHODS
  A three-arm randomised controlled trial with patient and assessor blinded to the group allocation. One hundred fifty patients with chronic, nonspecific low back pain from outpatient physical therapy clinics in Brazil. The patients will be randomly allocated into 3 groups (IFC 1 kHz, IFC 4 kHz or Placebo IFC). The interferential current will be applied three days per week (30 minutes per session) over four weeks.
  
  
  METHODS
  Pain intensity.
  
  
  RESULTS
  The pressure pain threshold, global impression of recovery, disability, function, conditioned pain modulation and temporal summation of pain, discomfort caused by the current. All outcomes will be measured at 4 weeks and 4 months after randomisation. The between-group differences will be calculated by using linear mixed models and Tukey's post-hoc tests.
  
  
  CONCLUSIONS
  The use of a placebo group and double-blinding assessor and patients strengthen this study. The present study is the first to compare different IFC carrier frequencies in patients with chronic low back pain.
  
  
  BACKGROUND
  Brazilian Registry of Clinical Trials: http://RBR-8n4hg2.
authors.affiliation: Master's and Doctoral Programs in Physical Therapy, Universidade Cidade de São Paulo (UNICID), São Paulo, Brazil.
authors.forename: Juliana Barbosa
authors.initials: JB
authors.lastname: Corrêa
authors.forename: Leonardo Oliveira Pena
authors.initials: LO
authors.lastname: Costa
authors.forename: Naiane Teixeira Bastos
authors.initials: NT
authors.lastname: de Oliveira
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Sluka
authors.forename: Richard Eloin
authors.initials: RE
authors.lastname: Liebano
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059350:Chronic Pain / Q000503:physiopathology / Q000534:rehabilitation*; D002985:Clinical Protocols; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000503:physiopathology / Q000534:rehabilitation*; D008297:Male; D008875:Middle Aged; D059408:Pain Management / Q000379:methods*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology; D012107:Research Design; D004561:Transcutaneous Electric Nerve Stimulation / Q000379:methods*; D055815:Young Adult